U.S. patent application number 11/004956 was filed with the patent office on 2005-07-28 for visual communications system and method of controlling the same.
This patent application is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Kutsuna, Masaki, Matsumoto, Yuichi, Mori, Shigeki, Yamamoto, Takashi.
Application Number | 20050166242 11/004956 |
Document ID | / |
Family ID | 34735847 |
Filed Date | 2005-07-28 |
United States Patent
Application |
20050166242 |
Kind Code |
A1 |
Matsumoto, Yuichi ; et
al. |
July 28, 2005 |
Visual communications system and method of controlling the same
Abstract
A visual communications system and a method of controlling the
same for pausing the screens of two terminals at quite the same
image. Video communications terminals receive the same channel in
their respective broadcast program receiving units. A first video
communications terminal temporarily stores the video of the
received channel in the temporary storage memory. When a user
pauses operation of the first terminal, it temporarily stores a
screen pause time obtained by adding a predetermined time to the
current time, and transmits a screen pause command and the screen
pause time to a second video communications terminal. The second
terminal pauses the video at the screen pause time if possible in
time. Otherwise, it pauses the video immediately, and transmits a
response with its own image pause time to the first terminal. The
first terminal displays an image corresponding to the image pause
time of the second terminal memory.
Inventors: |
Matsumoto, Yuichi;
(Fujisawa-shi, JP) ; Yamamoto, Takashi;
(Yamato-shi, JP) ; Kutsuna, Masaki; (Toyota-shi,
JP) ; Mori, Shigeki; (Koshiya-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
Canon Kabushiki Kaisha
Tokyo
JP
|
Family ID: |
34735847 |
Appl. No.: |
11/004956 |
Filed: |
December 7, 2004 |
Current U.S.
Class: |
725/88 ;
348/E7.081; 386/E5.001; 725/100; 725/102; 725/131; 725/139;
725/151 |
Current CPC
Class: |
H04N 5/76 20130101; H04N
21/4788 20130101; H04N 7/147 20130101; H04N 21/4325 20130101; H04N
21/4223 20130101 |
Class at
Publication: |
725/088 ;
725/100; 725/131; 725/139; 725/151; 725/102 |
International
Class: |
H04N 007/173; H04N
007/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2003 |
JP |
2003-416732 |
Claims
What is claimed is:
1. A visual communications system, comprising: a plurality of
communications terminals connected via a network, each of said
plurality of communications terminals comprising: a broadcast
receiving unit for receiving a broadcast wave and outputting video
data; and a control unit for enabling an image display based on the
video data, wherein, in response to an operation initiated by a
user's screen pause instruction, said control unit enables display
of a same static image by more than one of said plurality of
communication terminals.
2. A visual communications system according to claim 1, wherein
each of said plurality of communications terminals comprises: a
network control unit for controlling a connection state with
another of said plurality of connected communications terminals;
and a memory for storing video data for a predetermined period of
time based on a response from another of said plurality of
connected communications terminals received via said network
control unit.
3. A visual communications system, comprising: a plurality of
communications terminals connected via a network; and a plurality
of video playback units, each of said plurality of playback units
connected to one of said plurality of communications terminals,
respectively, each of said plurality of communications terminals
comprising: a control unit for enabling an image display based on
video data output from a corresponding one of said plurality of
video playback units, wherein in response to a user's playback
operation, said control unit enables display of a same image as one
displayed in another of said plurality of connected communications
terminals.
4. A visual communications system according to claim 3, wherein
each of said plurality of communications terminals comprises: a
network control unit for controlling a connection state with
another of said plurality of connected communications terminals;
and a memory for storing video data for a predetermined period of
time based on a response from another of said plurality of
connected communications terminals received via said network
control unit.
5. A visual communications system according to claim 4, wherein
said control unit transmits an instruction command for giving an
instruction of pausing a playback operation, and transmits pause
position information indicating a playback pause position in the
video data to the another of said plurality of connected
communications terminals in response to the user's playback pause
operation.
6. A visual communications system according to claim 5, wherein the
pause position information is a time obtained by adding a
predetermined time to a current time.
7. A visual communications system according to claim 5, wherein the
video data includes an identifier for identifying a frame, and the
pause position information is a frame identifier.
8. A visual communications system according to claim 5, wherein the
video data is recorded on a recording medium from which it can be
read out, and the pause position information is position
information on the recording medium.
9. A visual communications system according to claim 4, wherein at
least one of said plurality of communications terminals shifts a
playback start time by a time difference between a playback start
time of said corresponding video playback unit and a playback start
time of the video playback unit connected to said one of said
plurality of communications terminals before the playback.
10. A method of controlling a visual communications system
including a plurality of communications terminals connected via a
network, comprising the steps of: receiving a broadcast wave in one
of the plurality of communications terminals and outputting video
data therefrom; enabling an image display based on the video data;
and enabling a display of a same static image as one displayed in
another of the plurality of connected communications terminals in
response to a user's screen pause operation.
11. A method of controlling a visual communications system
including a plurality of communications terminals connected via a
network and video playback units connected to the communications
terminals, respectively, comprising the steps of: enabling an image
display based on video data output from the video playback unit in
one of the plurality of communications terminals; and enabling a
display of the same image as one displayed in another of the
plurality of connected communications terminals in response to a
user's playback operation.
12. A computer program for causing a computer to execute the method
of controlling the visual communications system according to claim
10.
13. A computer program for causing a computer to execute the method
of controlling the visual communications system according to claim
11.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a visual communications
system comprising communications terminals connected via a network
and a method of controlling the same.
[0003] 2. Description of the Related Art
[0004] There has been suggested an interactive-network,
simultaneous-viewing system enabling a user to view the same TV
program or the same video content as another party by using a TV
phone or the like, while enjoying a conversation about the movie or
the program they are viewing.
[0005] In this regard, transferring a control command requires a
certain amount of time and therefore, if one party pauses the
content while viewing the same content as the other party by using
the TV phone or the like, both parties cannot pause the content at
quite the same position.
[0006] Japanese Laid-Open Patent Publication (Kokai) No. H7-245594
(1995-245594), corresponding to U.S. Pat. No. 5,684,526, discloses
an arrangement in which time information about a user's responding
operation is added and sent to a destination over a telephone line
regarding a responding operation to a program, so that the
destination can accurately identify the responding operation time
of a plurality of users. The arrangement, however, does not resolve
the above problem.
[0007] If a pause occurs near a scene boundary of the content, the
content may pause before switching scenes for the one party, but
pause after switching scenes for the other party. In this
situation, the images displayed on their screens will be quite
different from each other, which may cause theme confusion in their
conversation about the program or the paused scene.
[0008] Furthermore, when playing back content recorded in a
recording medium, playback timings may be different between the
devices since a period of time needed for the playback varies with
the devices. This may cause a situation where they are talking
about different parts of the content while viewing the same
content.
[0009] It is an object of the present invention to provide a
controller and a video playback unit to eliminate these
disadvantages.
SUMMARY OF THE INVENTION
[0010] According to one aspect of the present invention, there is
provided a visual communications system, including a plurality of
communications terminals connected via a network. Each of the
communications terminals includes a broadcast receiving unit for
receiving a broadcast wave and outputting video data and a control
unit for enabling an image display based on the video data. The
control unit enables a display of the same static image as one
displayed in another of the connected communications terminals in
response to a user's screen pause operation.
[0011] According to another aspect of the present invention, a
visual communications system includes a plurality of communications
terminals connected via a network and video playback units
connected to the communications terminals, respectively. Each of
the communications terminals includes a control unit for enabling
an image display based on video data output from the video playback
unit. The control unit enables a display of the same image as one
displayed in another of the connected communications terminals in
response to a user's playback operation.
[0012] Another aspect of the present invention is directed to a
method of controlling a visual communications system that has a
plurality of communications terminals connected via a network. The
method includes the steps of: receiving a broadcast wave in one of
the communications terminals and outputting video data therefrom;
enabling an image display based on the video data; and enabling a
display of the same static image as one displayed in another of the
connected communications terminals in response to a user's screen
pause operation.
[0013] A further aspect of the present invention is directed to a
method of controlling a visual communications system including a
plurality of communications terminals connected via a network and
video playback units connected to the communications terminals,
respectively. The method includes the steps of: enabling an image
display based on video data output from the video playback unit in
one of the communications terminals; and enabling a display of the
same image as one displayed in another of the connected
communications terminals in response to a user's playback
operation.
[0014] Another aspect of the present invention is directed to a
computer-readable computer program prepared for causing the
computer to execute the aforementioned method of controlling the
visual communications system.
[0015] Therefore, according to the present invention, a plurality
of users can pause the video playback at quite the same position.
Even if the playback is paused near a scene boundary of the
content, the plurality of users can view the same image. Thereby,
the users can enjoy a conversation about quite the same image while
viewing that image.
[0016] Even through tape media or disk media, the same image is
played back and displayed on each of the media after releasing the
pause and the users can enjoy a conversation about the same image
while viewing the image.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is an outline block diagram of a first embodiment of
the present invention.
[0018] FIG. 2 is an illustration of an operation between a terminal
100 and a terminal 300 in case 1 of the first embodiment.
[0019] FIG. 3 is an illustration of an operation between the
terminal 100 and the terminal 300 in case 2 of the first
embodiment.
[0020] FIG. 4 is an illustration of an operation between the
terminal 100 and the terminal 300 in case 3 of the first
embodiment.
[0021] FIG. 5 is an outline block diagram of a second
embodiment.
[0022] FIG. 6 is an illustration of a screen of a display unit
180.
[0023] FIG. 7 is an illustration of an operation between a terminal
100a and a terminal 300a.
[0024] FIG. 8 is another illustration of an operation between the
terminal 100a and the terminal 300a.
[0025] FIG. 9 is an illustration of an operation between the
terminal 100 and the terminal 300 of a third embodiment.
[0026] FIG. 10 is an outline block diagram of a fourth
embodiment.
[0027] FIG. 11 is an illustration of an operation between a
terminal 100b and a terminal 300b.
[0028] FIG. 12 is an illustration of an operation between the
terminal 100 and the terminal 300 of a fifth embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] Preferred embodiments of the present invention will be
described in detail in accordance with the accompanying
drawings.
First Embodiment
[0030] Referring to FIG. 1, there is shown an outline block diagram
of a first embodiment of the present invention. A user A uses a
video communications terminal 100 as communications terminal
equipment and a user B uses a video communications terminal 300.
Television cameras 105 and 305 are for use in shooting video of the
users A and B, respectively. Although the video communications
terminal 100 and the video communications terminal 300 have the
same configuration and functions, the video communications terminal
100 is assumed here to initiate the operation. The configuration
and functions of the video communications terminals 100 and 300
will be described below.
[0031] A broadcast program receiving unit 110 has the same
configuration as a general digital television. A tuner 112 receives
a signal from an antenna 111, demodulates the received data and
corrects any error, and outputs transport stream (TS) data. A
demultiplexer 113 separates desired video data, audio data, and
subtitle character information from TS data including time-division
multiplexed data of video and audio data, subtitle character
information, and electronic program data, or the like, of a
plurality of channels. The separated video data is sent to a video
decoder 114, and then decoded. The audio data separated by the
demultiplexer 113 is sent to an audio decoder (not shown), and then
output to an audio output unit (not shown), such as, for example, a
speaker.
[0032] A temporary storage memory 115 temporarily stores a
plurality of frames of video data output from the video decoder
114. The video data output from the video decoder 114 is input to a
video composition unit 170 via the temporary storage memory 115.
The video data decoded by the video decoder 114 is displayed on a
display unit 180 by the video composition unit 170. The video
composition unit 170 is capable of displaying a static image on the
display unit 180 based on the video from the temporary storage
memory 115.
[0033] A CODEC 140 compresses and decompresses video and audio
data. The CODEC 140 compresses output video of the television
camera 105 and outputs it to a network control unit (NCU) 150. In
addition, it decompresses the compressed video data input from the
NCU 150. The NCU 150 controls connections on a communication line
400.
[0034] The communication line 400 is an ISDN, and the NCU 150 is
configured so as to operate conforming to ITU H320 standard.
Therefore, video output from the CODEC 140 or a CODEC 340 and other
control commands or the like can be transferred on the
communication line 400.
[0035] A control unit 190 appropriately controls blocks in the
video communications terminal 100. For example, it changes a
channel of the broadcast program receiving unit 110 according to an
operation of a remote controller (not shown) or an operation unit
(not shown). The control unit 190 further changes a channel of the
broadcast program receiving unit 110 according to a control command
received by the NCU 150.
[0036] The control unit 190 includes a microcomputer caused to
perform processing by a computer program.
[0037] The configuration of the video communications terminal 300
used by user B is the same as that of the video communications
terminal 100, except that it does not have a part corresponding to
the temporary storage memory 115.
[0038] Specifically, the video communications terminal 300 includes
a broadcast program receiving unit 310 having the same
configuration as a general digital television. The broadcast
program receiving unit 310 includes a tuner 312 that receives the
signal from an antenna 311, demodulates the received data and
corrects any error, and outputs transport stream (TS) data.
Demultiplexer 313 in the broadcast program receiving unit 310
separates desired video data, audio data, and subtitle character
information from TS data including time-division multiplexed data
of video and audio data, subtitle character information, and
electronic program data, or the like, of a plurality of channels.
The separated video data is sent to a video decoder 314, and then
decoded. The video data output from the video decoder 314 is input
to a video composition unit 370 and displayed on a display unit 380
by the video composition unit 370. The video composition unit 370
is capable of displaying a static image on the display unit
380.
[0039] In a digital broadcast, generally a system clock reference
(SCR) and a program clock reference (PCR) are broadcast, by which
it is possible to obtain and correct time information. Therefore,
the video communications terminal 100 and the video communications
terminal 300 can obtain the same time and operate based on the same
time.
[0040] The operation between the video communications terminals 100
and 300 will be described in detail below. It is assumed that a
line connection is completed between the video communications
terminals 100 and 300, using communication line 400, for
example.
[0041] The user A is assumed to have selected a certain channel.
The control unit 190 sets the channel as a receiving channel of the
broadcast program receiving unit 110 and transmits a channel select
command to the video communications terminal 300 via the CODEC 140
and the NCU 150. The control unit 390 of the video communications
terminal 300 receives the channel select command via the NCU 350
and the CODEC 340. It then sets a receiving channel of the
broadcast program receiving unit 310 to a channel specified by the
channel select command, namely, a channel selected by the user
A.
[0042] The video composition unit 170 combines an image of the
television camera 305 received via the CODEC 340, the NCU 350, the
NCU 150, and the CODEC 140 with an image from the broadcast program
receiving unit 110 and displays the composite image on the display
unit 180. FIG. 2 illustrates an example of the screen of the
display unit 180 at that time. The video communications terminal
300 operates in the same manner and displays the same screen on
display unit 380.
[0043] In this condition, the user A is assumed to have made an
operation of pausing the screen. Thereupon, the control unit 190 of
the video communications terminal 100 identifies the current time
and temporarily stores the time obtained by adding a predetermined
time to the current time as a screen pause time. Subsequently, the
control unit 190 outputs a screen pause command and the temporarily
stored screen pause time to the video communications terminal 300
via the CODEC 140 and the NCU 150. The control unit 390 of the
video communications terminal 300 receives the screen pause command
and the screen pause time via the NCU 350 and the CODEC 340.
[0044] The timing of the screen pause command gives rise to three
cases. In the first case (case 1) the video communications terminal
300 receives the screen pause command before the screen pause time
and the video communications terminal 100 receives a response to
the screen pause command before the screen pause time. In the
second case, the video communications terminal 300 receives the
screen pause command before the screen pause time and the video
communications terminal 100 receives a response to the screen pause
command after the screen pause time. In the third case, the video
communications terminal 300 receives the screen pause command after
the screen pause time. Considering the processing time for the
screen pause in the video communications terminal 300, the
following case is treated in the same way as case 3: a case where a
time period from the time when a reception of the screen pause
command from the video communications terminal 100 is designated to
the screen pause time designated by the screen pause command is
shorter than the processing time for the screen pause in the video
communications terminal 300.
[0045] FIG. 2 illustrates a communication between the video
communications terminals 100 and 300 in case 1. The control unit
390 of the video communications terminal 300 has enough time until
the received screen pause time and thus can pause the screen at the
screen pause time. Therefore, it sends a response to the screen
pause command to the video communications terminal 100 via the
CODEC 340 and the NCU 350, together with the time when the screen
is paused in the video communications terminal 300, namely, the
received screen pause time. Then, at the screen pause time, the
control unit 390 controls the video composition unit 370 to pause
the screen. At the other side of the network, the video
communications terminal 100 receives the response to the screen
pause command and the screen pause time of the video communications
terminal 300 and controls the video composition unit 170 to pause
the screen at the received screen pause time.
[0046] As shown in FIG. 2, when the screen pause operation is
executed by a user at video communications terminal 100 at time t,
a screen pause command is transmitted to video communications
terminal 300 instructing that video communications terminal 300
pause the screen of display unit 380 at a time equal to t+.alpha..
That screen pause command is received at video communications
terminal 300 after time t and before time t+.alpha.. Video
communications terminal 300 then sends a response to video
communications terminal 100 confirming that video communications
terminal 300 will pause the display at time t+.alpha.. As
illustrated in FIG. 2, video communications terminal 100 receives
the response from video communications terminal 300 before time
t+.alpha.. Then, at time t+.alpha., both video communications
terminals 100 and 300 pause the screen in their respective display
units at time t+.alpha..
[0047] Accordingly, the video communications terminals 100 and 300
can pause the screens at quite the same image. Therefore, even if
the pause occurs near a scene boundary of the content, the same
image is displayed on both screens. Therefore, the users A and B
can enjoy a conversation about the same image while viewing that
image.
[0048] FIG. 3 illustrates a communication between the video
communications terminals 100 and 300 in case 2. An operation of the
video communications terminal 300 in this case is the same as in
case 1.
[0049] In case 2, the user executes a screen pause operation at
video communications terminal 100 at time t. The screen pause
command instructs video communications terminal 300 to pause at
time t+.alpha.. The command reaches video communications terminal
300 before time t+.alpha., and terminal 300 pauses the screen of
display unit 380 at t+.alpha.. However, the response by video
communications terminal 300 to the screen pause command does not
reach video communications terminal 100 until after time
t+.alpha..
[0050] In case 2, since the video communications terminal 100 did
not receive a response to the screen pause command by the screen
pause time of t+.alpha., it controlled the video composition unit
170 to pause the screen at the screen pause time, and began storing
video data subsequent to the screen pause time from the video
decoder 114 into the temporary storage memory 115. Thereafter, when
the video communications terminal 100 received a response to the
screen pause command and a screen pause time of t+.alpha. from the
video communications terminal 300. The video communications
terminal 100, however, does nothing at that time since the received
screen pause time of t+.alpha. is the same as the time when it
paused its own screen.
[0051] Accordingly, the video communications terminals 100 and 300
can pause the screens at quite the same image, thereby achieving
the same effect as in case 1.
[0052] FIG. 4 illustrates a communication between the video
communications terminals 100 and 300 in case 3. In case 3, the user
executes the screen pause operation at time t at video
communications terminal 100, instructing video communications
terminal 300 to pause at time t+.alpha.. However, video
communications terminal 300 does not receive the screen pause
command until after time t+.alpha.. At time t+.beta., which is
later than time t+.alpha., video communications terminal 300 pauses
the screen of display unit 380. Since video communications terminal
100 did not receive a response from video communications terminal
300 by time t+.alpha., at time t+.alpha., video communications
terminal 100 paused the screen of display unit 180, and began
storing video information. After pausing the screen of display unit
380 at time t+.beta., video communications terminal 300 responds to
the screen pause command and provides its pause time of t+.beta. to
video communications terminal 100. In case 3, the control unit 390
of the video communications terminal 300 immediately pauses the
screen at time t+.beta. since the received screen pause time is
past the current time. Then, the control unit 390 outputs a
response to the screen pause command to the video communications
terminal 100 via the CODEC 340 and the NCU 350, together with the
time t+.beta. when the video communications terminal 300 paused its
own screen.
[0053] The video communications terminal 100 receives the response
to the screen pause command and the screen pause time of the video
communications terminal 300 after the screen pause time t+.alpha.
temporarily stored. At time t+.alpha., the video communications
terminal 100 controls the video composition unit 170 to pause the
screen and starts storing the image data from the video decoder 114
into the temporary storage memory 115. When terminal 300 receives
the response to the screen pause command and the screen pause time
t+.beta. of the video communications terminal 300 from the video
communications terminal 300, the control unit 190 controls the
video composition unit 370 to cause the display unit 380 to display
an image at the time corresponding to the screen pause time
t+.beta. of the video communications terminal 300 in the temporary
storage memory 115.
[0054] Accordingly, the video communications terminals 100 and 300
can pause the screens at quite the same image in the same manner as
for cases 1 and 2 and the same effects can be achieved as for cases
1 and 2.
Second Embodiment
[0055] A second embodiment of the present invention will be
described hereinafter. FIG. 5 shows an outline block diagram of the
second embodiment. The same reference numerals have been retained
for the same parts as those shown in FIG. 1.
[0056] A video communications terminal 100a has a function of
controlling a video cassette recorder (VCR) 120 as a video playback
unit to capture the played back video, in addition to the functions
of the video communications terminal 100a. The VCR 120 plays back
the content recorded on the cassette tape. A control unit 190a of
the video communications terminal 100a can control the playback,
stop, pause and other operations of the VCR 120. The video
communications terminal 100a and the VCR 120 are connected via, for
example, an IEEE 1394 serial bus standardized as the IEEE 1394-1995
standard by the Institute of Electrical and Electronics Engineers,
Inc., the video and audio data are transferred as isochronous data,
and a control command of the VCR 120 is transferred as asynchronous
data. In the 1394 Trade Association (1394RA), a control command and
a control method (protocol) for use in the IEEE 1394 serial bus are
defined. For details, refer to "AV/C Digital Interface Command Set
General Specification," "AV/C Digital Interface Command Set VCR
Subunit Specification," or other written standards issued by the
1394TA.
[0057] The control command from the control unit 190a can be
transmitted outside through the NCU 150. Furthermore, the control
unit 190a controls the VCR 120 according to the control command
received by the NCU 150. A temporary storage memory 125 temporarily
stores video data output from the VCR 120 under the control of the
control unit 190a.
[0058] A video communications terminal 300a controls a video
cassette recorder (VCR) 320 and has a function of capturing its
played back video, in addition to the function of the video
communications terminal 300a. In other words, the video
communications terminal 300a and the video communications terminal
100a have substantially the same functions. A temporary storage
memory 325 temporarily stores video data output from the VCR 320
under the control of the control unit 390a.
[0059] The VCRs 120 and 320 are assumed to have cassette tapes
having the same content recorded therein, respectively.
[0060] The operation between the video communications terminals
100a and 300a will be described below. It is assumed that a line
connection is completed between the video communications terminals
100a and 300a by communication line 400.
[0061] The user A is assumed to have performed an operation for
playing the VCR 120. Thereon, the control unit 190a controls the
VCR 120 to be put into a playback state and transmits a playback
command to the video communications terminal 300a via the CODEC 140
and the NCU 150. The control unit 390a of the video communications
terminal 300a controls the VCR 320 to be put into the playback
state according to the playback command received via the NCU 350
and the CODEC 340.
[0062] A video composition unit 170 combines an image of a
television camera 305 received via the CODEC 340, the NCU 350, the
NCU 150, and the CODEC 140 with a played back image on the VCR 120
and displays the composite image on a display unit 180, in the same
manner as in the illustrative screen shown in FIG. 6. The video
communications terminal 300a operates similarly and displays the
same image in a display unit 380 as in the illustrative screen in
FIG. 6.
[0063] In this condition, the user A is assumed to have performed
an operation of pausing the VCR 120. Thereupon, the control unit
190a controls the VCR 120 to be put into a pause state and
identifies the position on the paused tape of the VCR 120. This
operation can be performed using an absolute track number command
of an AV/C command. Then, the control unit 190a transmits a pause
command and a pause position of the VCR 120 to the video
communications terminal 300a via the CODEC 140 and the NCU 150.
[0064] The control unit 390a of the video communications terminal
300a receives the pause command and the pause position via the NCU
350 and the CODEC 340 and pauses the VCR 320 at the pause position.
It is enabled by the absolute track number command of the AV/C
command.
[0065] Accordingly, the VCR 120 of the user A and the VCR 320 of
the user B can be paused at quite the same position, thereby
achieving the same effects as for the first embodiment.
[0066] While the pause position on the tape has been used in the
above description, a frame ID can be used instead of the position
on the tape in an arrangement where a frame ID is added to each
frame in the content and the video communications terminals 100a
and 300a are capable of identifying the frame ID.
[0067] The user A is then assumed to give an instruction of playing
the VCR 120 during a pause of both terminals. Thereon, the control
unit 190a of the video communications terminal 100a controls the
VCR 120 to be put into a playback state and transmits a playback
command to the video communications terminal 300 via the CODEC 140
and the NCU 150. When the VCR 120 starts to play back the video,
the video communications terminal 100a transmits the playback start
time to the video communications terminal 300a.
[0068] Upon receiving the playback command via the NCU 350 and the
CODEC 340, the control unit 390a of the video communications
terminal 300a controls the VCR 320 to be put into a playback state.
Then, when the VCR 320 starts to play back the video, the terminal
300a transmits the playback start time to the video communications
terminal 100a.
[0069] FIG. 7 illustrates a situation in which that t1 and t2 are
the playback start time of the VCR 120 and the playback start time
of the VCR 320, respectively, and t1 is earlier than t2 (t1<t2).
The video communications terminal 100a, having the earlier playback
start time, starts to store the video output from the VCR 120 into
the temporary storage memory 125. After storing the video having a
length equivalent to t2 minus t1 (t2-t1) into the temporary storage
memory 125, it then starts to read a video signal from the
temporary storage memory 125 to the video composition unit 170.
[0070] FIG. 8 illustrates a situation in which the VCR 320 starts
the video playback earlier than the VCR 120, in other words,
t1>t2. In this situation, the video communications terminal 300,
having the earlier playback start time, starts to store the video
output from the VCR 320 into the temporary storage memory 325.
Then, after storing the video having a length equivalent to t1
minus t2 (t1-t2) into the temporary storage memory 325, it then
starts to read a video signal from the temporary storage memory 325
to the video composition unit 370.
[0071] Accordingly, quite the same image can be displayed on the
screens of the video communications terminals 100a and 300a.
[0072] In the above description, if the VCR 120 and the VCR 320
each have an apparatus having sufficiently quick response such as a
hard disk storage unit, the video communications terminal 100a does
not need the temporary storage memory 125, but it is only necessary
to change (rewind) the playback position backward by the amount of
time equivalent to the time "t2-t1." Alternatively, the video
communications terminal 300 having the later playback start time
may change (fast-forward) the playback position by the amount of
time equivalent to the time "t2 -t1." The same is true of the video
communications terminal 300a.
[0073] While the video communications terminal 100a and the video
communications terminal 300a obtain the same time from the
broadcast program receiving units 110 and 310 in this embodiment,
the arrangement may be such that the video communications terminals
100a and the video communications terminal 300a obtain the same
time from the JJY standard frequency broadcast managed by the
Communications Research Laboratory.
[0074] Those skilled in the art will readily understand that the
invention is not limited to VCR's, but may be used with other
devices capable of recording and playing back video data, such as
DVD players, CD ROM players, and the like.
Third Embodiment
[0075] FIG. 9 illustrates the operation of a third embodiment of
the present invention which involves a change in operation from the
first embodiment. Therefore, the following describes only the
changes with reference to FIG. 9.
[0076] It is assumed that the user A performed a screen pause
operation at time t. At that time, the control unit 190 controls
the video composition unit 170 to pause the screen and transmits
the screen pause command to the video communications terminal 300
via the CODEC 140 and the NCU 150. Then, the video communications
terminal 100 awaits a response from the video communications
terminal 300 and starts the temporary storage of the video data
from the video decoder 114.
[0077] Upon receiving the screen pause command via the NCU 350 and
the CODEC 340, the control unit 390 of the video communications
terminal 300 controls the video composition unit 370 to pause the
screen and identifies the current time of t+.alpha.. The video
communications terminal 300 transmits the screen pause time of the
video communications terminal 300, t+.alpha., to the video
communications terminal 100 via the CODEC 340 and the NCU 350,
together with a response to the screen pause command.
[0078] Upon receiving the response to the screen pause command and
the screen pause time of the video communications terminal 300 via
the NCU 150 and the CODEC 140, the control unit 190 of the video
communications terminal 100 controls the video composition unit 370
and displays the video at the time corresponding to the screen
pause time of the video communications terminal 300, that is, time
t+.alpha., from the video data temporarily stored.
[0079] Accordingly, the video communications terminal 100 and the
video communications terminal 300 can pause the screen at quite the
same image, thereby achieving the same effects as for the first
embodiment. Furthermore, in comparison with the first embodiment,
the screen pauses in a shorter time from the screen pause operation
of the user A of the video communications terminal 100 and
therefore a convenient operating environment is available. Still
further, in comparison with the second embodiment, the video
communications terminal 100 need not temporarily store the screen
pause time and it becomes unnecessary to compare it with the screen
pause time of the video communications terminal 300, by which the
operation is simplified.
Fourth Embodiment
[0080] A fourth embodiment of the present invention will be
described below. Referring to FIG. 10, there is shown an outline
block diagram of the fourth embodiment. The fourth embodiment
differs from the first embodiment in that a video communications
terminal 300b also needs a temporary storage memory 315. The
temporary storage memory 315 can store a number of frames of video
data output from the video decoder 314. In this embodiment, the
temporary storage memory 315 constantly contains temporarily stored
video data output from the video decoder 314.
[0081] It is assumed that the user A performed a screen pause
operation. An operation between the video communications terminals
100b and 300b is shown in FIG. 11.
[0082] According to the operation of the user A, a control unit
190b of a video communications terminal 100b identifies the current
time and temporarily stores a time obtained by adding a
predetermined time to the current time as a screen pause time t.
Subsequently, the control unit 190b transmits a screen pause
command, together with the screen pause time t, to the video
communications terminal 300b via a CODEC 140 and an NCU 150. Then,
the video communications terminal 100b awaits a response from the
video communications terminal 300b and starts to temporarily store
the output video data from the video decoder 114 into the temporary
storage memory 115.
[0083] Upon receiving a screen pause command via the NCU 350 and
the CODEC 340, the control unit 390b of the video communications
terminal 300b controls the video composition unit 370 and reads and
displays the image at the screen pause time t in the video stored
in the temporary storage memory 315. The control unit 390b
transmits a response to the screen pause command to the video
communications terminal 100b via the CODEC 340 and the NCU 350,
together with the screen pause time of the video communications
terminal 300b, namely, the screen pause time t transmitted from the
video communications terminal 100.
[0084] The video communications terminal 100b receives the response
to the screen pause command and the screen pause time of the video
communications terminal 390b from the video communications terminal
300b. Since the received screen pause time is the same as the
screen pause time of the video communications terminal 100b, the
video communications terminal 100b does nothing at that time.
[0085] Accordingly, the video communications terminal 100b and the
video communications terminal 300b can pause the screens at quite
the same image, thereby achieving the same effects as for the third
embodiment. Furthermore, in comparison with the third embodiment,
the screen can be paused in a shorter time from the screen pause
operation of the user A and therefore a convenient operating
environment is available.
Fifth Embodiment
[0086] FIG. 12 illustrates the operation of a fifth embodiment of
the present invention. The configuration of the fifth embodiment is
substantially the same as that of the third embodiment. The
following describes changes from the third embodiment.
[0087] It is assumed that the user A performed a screen pause
operation. An operation between the video communications terminals
100 and 300 is shown in FIG. 12.
[0088] According to this operation, a control unit 190 identifies
the current time, pauses the screen, and transmits a screen pause
command and the identified time to a video communications terminal
300 via a CODEC 140 and an NCU 150. Then, the video communications
terminal 100 awaits a response from the video communications
terminal 300 and stores video data from a video decoder 114 into a
temporary storage memory 115 at regular time intervals (100 ms
here). In this regard, the time interval 100 ms for the temporary
storage into the temporary storage memory 115 is predetermined by
agreement between the video communications terminal 100 and the
video communications terminal 300.
[0089] A control unit 390 of a video communications terminal 300
receives the screen pause command and the time via an NCU 350 and a
CODEC 340. At the current time corresponding to the received time
plus an integral multiple of 100 ms, the control unit 390 controls
the video composition unit 370 to pause the screen. It then
transmits a response to the screen pause command to the video
communications terminal 100 via the CODEC 340 and the NCU 350,
together with the screen pause time of the video communications
terminal 300.
[0090] Upon receiving the response to the screen pause command and
the screen pause time of the video communications terminal 300 via
the NCU 150 and the CODEC 140, the control unit 190 of the video
communications terminal 100 controls the video composition unit 370
to read and display the image at the time corresponding to the
screen pause time of the video communications terminal 300 from the
video data stored in the temporary storage memory 115.
[0091] Accordingly, the video communications terminal 100 and the
video communications terminal 300 can pause the screens at quite
the same image, thereby achieving the same effects as for the first
an third embodiments.
[0092] In the fifth embodiment, the temporary storage memory 115
requires less capacity than in the third embodiment, since video
data from the video decoder 114 is stored at regular time intervals
(100 ms here) from when the video communications terminal 100
outputs the screen pause command to the video communications
terminal 300 until it receives the response to the screen pause
command.
[0093] Although the time intervals for the temporary storage of the
video data from the video decoder 114 into the temporary storage
memory 115 are predetermined with an agreement between the video
communications terminal 100 and the video communications terminal
300 in this embodiment, the predetermination becomes unnecessary by
adding it to the screen pause command. The arrangement may be such
that the screen pause command includes time information on the
temporary storage such as, for example, the pause time t, t+75 ms,
t+150 ms, t+225 ms, t+300 ms, and so on, and the video
communications terminal 300, having received the time information,
pauses the screen at the time corresponding to one of the time
information.
[0094] Except as otherwise disclosed herein, the various components
shown in outline or block form in the figures are individually
well-known and their internal construction and operation are not
critical either to the making or using of this invention or to a
description of the best mode of the invention.
[0095] While the present invention has been described with respect
to what is presently considered to be the preferred embodiments, it
is to be understood that the invention is not limited to the
disclosed embodiments. To the contrary, the present invention is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims. The
scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications,
equivalent structures and functions.
[0096] This application claims priority from Japanese Patent
Application No. 2003-416732 filed Dec. 15, 2003, which is hereby
incorporated by reference herein.
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